U.S. patent number 11,440,278 [Application Number 16/633,574] was granted by the patent office on 2022-09-13 for process and apparatus for applying noise reducer elements to tyres for vehicle wheels.
This patent grant is currently assigned to PIRELLI TYRE S.P.A.. The grantee listed for this patent is PIRELLI TYRE S.P.A.. Invention is credited to Albert Berenguer, Ivan Gildo Boscaino, Gianni Mancini, Cristiano Puppi.
United States Patent |
11,440,278 |
Boscaino , et al. |
September 13, 2022 |
Process and apparatus for applying noise reducer elements to tyres
for vehicle wheels
Abstract
A process and apparatus for applying noise reducer elements to
tyres. Each noise reducer element has an anchoring surface coated
with an adhesive layer. The anchoring surface is illuminated with a
reference radiation. The radiation emitted by the anchoring surface
is detected; and a digital image representative of the anchoring
surface is determined as a function of the emitted radiation. Each
pixel of the digital image is associated with a respective
brightness value representative of the amount of adhesive present
in an area of the anchoring surface corresponding to such each
pixel. One or more noise reducer elements are applied on the
radially inner surface of a tyre.
Inventors: |
Boscaino; Ivan Gildo (Milan,
IT), Berenguer; Albert (Milan, IT), Puppi;
Cristiano (Milan, IT), Mancini; Gianni (Turin,
IT) |
Applicant: |
Name |
City |
State |
Country |
Type |
PIRELLI TYRE S.P.A. |
Milan |
N/A |
IT |
|
|
Assignee: |
PIRELLI TYRE S.P.A. (Milan,
IT)
|
Family
ID: |
1000006558045 |
Appl.
No.: |
16/633,574 |
Filed: |
June 27, 2018 |
PCT
Filed: |
June 27, 2018 |
PCT No.: |
PCT/IB2018/054738 |
371(c)(1),(2),(4) Date: |
January 23, 2020 |
PCT
Pub. No.: |
WO2019/021080 |
PCT
Pub. Date: |
January 31, 2019 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
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US 20200164603 A1 |
May 28, 2020 |
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Foreign Application Priority Data
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|
|
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Jul 28, 2017 [IT] |
|
|
102017000086952 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N
21/8422 (20130101); B29D 30/0061 (20130101); G01N
2021/845 (20130101); G01N 2021/8427 (20130101) |
Current International
Class: |
B29D
30/00 (20060101); G01N 21/84 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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Sep 2007 |
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106030275 |
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Oct 2016 |
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CN |
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106345653 |
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Jan 2017 |
|
CN |
|
106457713 |
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Feb 2017 |
|
CN |
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0738886 |
|
Oct 1996 |
|
EP |
|
2554617 |
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Feb 2013 |
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EP |
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H06155627 |
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Jun 1994 |
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JP |
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2003075343 |
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Mar 2003 |
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JP |
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2008006783 |
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Jan 2008 |
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JP |
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2010030243 |
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Feb 2010 |
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JP |
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2017083279 |
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May 2017 |
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JP |
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2497687 |
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Nov 2013 |
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RU |
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02/28973 |
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Apr 2002 |
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WO |
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2012/007782 |
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Jan 2012 |
|
WO |
|
2015/092659 |
|
Jun 2015 |
|
WO |
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2016/067192 |
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May 2016 |
|
WO |
|
2017/082162 |
|
May 2017 |
|
WO |
|
Other References
First Chinese Office Action for CN Application No. 201880048808
filed on Jun. 27, 2018 on behalf of Pirelli Tyre S.P.A. dated Jun.
22, 2021 17 pages (English + Original). cited by applicant .
Russian Office Action for RU Application No. 2020107313 filed on
Jun. 27, 2018 on behalf of Pirelli Tyre S.P.A. dated Oct. 8, 2021
15 pages (English + Original). cited by applicant .
Second Chinese Office Action for CN Application No. 201880048808.3
filed on Jun. 27, 2018 on behalf of Pirelli Tyre S.P.A. dated Dec.
20, 2021 9 pages (English + Original). cited by applicant .
International Search Report for International Application No.
PCT/IB2018/054738 filed on Jun. 27, 2018 on behalf of Pirelli Tyre
S.P.A dated Sep. 18, 2018 5 pages. cited by applicant .
Written Opinion for International Application No. PCT/IB2018/054738
filed on Jun. 27, 2018 on behalf of Pirelli Tyre S.P.A dated Sep.
18, 2018 6 pages. cited by applicant .
Chinese Notice of Allowance for CN Application No. 201880048808.3
filed on Jun. 27, 2018 on behalf of Pirelli Tyre S.P.A. dated May
7, 2022 6 pages (English + Original). cited by applicant .
Japanese Office Action for JP Application No. 2020503014 filed on
Jun. 27, 2018 on behalf of Pirelli Tyre S.P.A. dated Apr. 19, 2022
5 pages (English + Original). cited by applicant.
|
Primary Examiner: Porta; David P
Assistant Examiner: Gutierrez; Gisselle M
Attorney, Agent or Firm: Steinfl + Bruno LLP
Claims
The invention claimed is:
1. A process for applying noise reducer elements to tyres, wherein
each noise reducer element comprises an anchoring surface coated
with an adhesive layer, comprising: illuminating said anchoring
surface coated with said adhesive layer with a reference radiation;
and detecting a radiation emitted by the anchoring surface
illuminated by the reference radiation and, as a function of said
emitted radiation, determining a digital image representative of
the anchoring surface coated with said adhesive layer, each pixel
of the digital image being associated with a respective brightness
value representative of the amount of adhesive present in an area
of said anchoring surface corresponding to said each pixel,
calculating as a function of the brightness values at least one
first parameter representative of the overall distribution of said
adhesive layer on the anchoring surface, performing a comparison
between a value of said at least one first parameter and at least
one reference value representative of a correct distribution of
said adhesive layer on the anchoring surface, based on said
comparison, applying on the radially inner surface of a tyre or
direct along a discard path one or more noise reducer elements.
2. A process as claimed in claim 1, wherein said illuminating said
anchoring surface takes place at a reading window.
3. A process as claimed in claim 1, further comprising positioning
said noise reducer element with the anchoring surface thereof
resting against a first transport surface movable according to a
predetermined advancement direction.
4. A process as claimed in claim 3, further comprising transferring
the noise reducer element from the first transport surface to a
second transport surface movable according to the advancement
direction consecutively to the first transport surface.
5. A process as claimed in claim 4, wherein illuminating said
anchoring surface takes place during transferring the noise reducer
element.
6. A process as claimed in claim 4, wherein said illuminating said
anchoring surface takes place at a reading window defined between
the first transport surface and the second transport surface.
7. A process as claimed in claim 1, wherein said digital image
comprises a plurality of image units and performing a comparison
between the value of said at least one first parameter with said at
least one reference value is performed for each image unit.
8. A process as claimed in claim 1, wherein said digital image
comprises a plurality of image units and wherein performing a
comparison is performed as a function of an acceptability
threshold, said acceptability threshold comprising at least one
from among: an absolute acceptability parameter defined by a
predetermined number of image units for which the value of said at
least one first parameter does not conform to said at least one
reference value; a relative acceptability parameter defined by a
predetermined percentage of image units for which the value of said
at least one first parameter does not conform to said at least one
reference value with respect to the total number of image units of
said digital image; an aggregative acceptability parameter defined
by a predetermined quantity of image units that are respectively
adjacent, for which the value of said at least one first parameter
does not conform to said at least one reference value.
9. A process as claimed in claim 1, wherein determining a digital
image is carried out by generating, during the transfer of each
noise reducer element, a plurality of frames each representative of
a portion of the anchoring surface.
10. A process as claimed in claim 9, further comprising positioning
said noise reducer element with the anchoring surface thereof
resting against a first transport surface movable according to a
predetermined advancement direction, wherein said illuminating said
anchoring surface takes place at a reading window, wherein the
determining a digital image is repeated at a frequency defined as a
function of the ratio of a transfer speed of the noise reducer
element along the advancement direction to a longitudinal dimension
of the reading window in the advancement direction.
11. A process as claimed in claim 2, wherein a screen arranged
adjacent to said reading window, when illuminated by the reference
radiation, emits a background radiation whose acquisition is
discriminable with respect to the radiation emitted by the
anchoring surface.
12. A process as claimed in claim 11, further comprising detecting
the background radiation emitted by said screen, together with the
radiation emitted by the anchoring surface, and discriminating in
said digital image a first portion representative of the anchoring
surface and a second portion representative of the screen.
13. A process as claimed in claim 12, further comprising detecting
the quantity of image units for which the value of said at least
one first parameter does not conform to said at least one reference
value, and excluding the image units of the second portion
representative of the screen.
14. A process as claimed in claim 4, wherein said illuminating said
anchoring surface takes place at a reading window, the process
further comprising detecting an alignment of a front edge of the
noise reducer element with a rear edge of the reading window and
synchronising the determining a digital image with the transfer of
the noise reducer element as a function of the alignment detected.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
The present application is the U.S. National Stage of International
Patent Application No. PCT/IB2018/054738 filed on Jun. 27, 2018
which, in turn, claims priority to Italian Application No.
102017000086952 filed on Jul. 28, 2017.
The present invention relates to a process and an apparatus for
applying noise reducer elements to tyres for vehicle wheels.
The expression "noise reducer element" is used for indicating an
element that, once associated with a tyre for vehicle wheels, has
the capacity of attenuating the noise produced by the tyre during
use. Such capacity is preferably conferred to the aforesaid noise
reducer element by the type of material with which the aforesaid
element is made. A material suitable for such purpose is for
example a sound-absorbent material, such as open-cell polyurethane
foam.
A tyre for vehicle wheels generally comprises a carcass structure
comprising at least one carcass ply formed by reinforcement cords
incorporated in a matrix of elastomeric material. The carcass ply
has end flaps respectively engaged with anchoring annular
structures. The latter are situated in the zones of the tyre
normally identified with the term "beads" and each is normally
formed by a substantially circumferential annular insert on which
at least one filler insert is applied, in radially outer position.
Such annular inserts are commonly known as "bead cores" and have
the task of maintaining the tyre firmly fixed to the anchoring seat
suitably provided in the rim of the wheel, thus preventing, during
operation, the exit of the radially inner end flap of the tyre from
such seat.
At the beads, specific reinforcement structures can be provided
having the function of improving the transmission of torque to the
tyre.
In radially outer position with respect to the carcass structure, a
crown structure is associated.
The crown structure comprises a belt structure and, in radially
outer position with respect to the belt structure, a tread band
made of elastomeric material.
The belt structure comprises one or more belt layers, situated in
radial superimposition with respect to each other and having
textile or metallic reinforcement cords with cross orientation
and/or substantially parallel to the circumferential extension
direction of the tyre.
Between the carcass structure and the belt structure, a layer of
elastomeric material can be provided, termed "under-belt", having
the function of making the radially outer surface of the carcass
structure as uniform as possible for the subsequent application of
the belt structure.
Between the belt structure and the tread band, a so-called
"underlayer" can be interposed that is made of elastomeric material
with properties suitable for ensuring a stable joining of the tread
band to the belt structure.
Respective sidewalls of elastomeric material are applied on the
lateral surfaces of the carcass structure, each extended from one
of the lateral edges of the tread band up to the respective
anchoring annular structure of the beads.
The expression "advancement direction" is used for indicating a
direction parallel to the longitudinal direction of a conveyor
belt, for feeding or gluing. The feeding direction thus corresponds
with the advancement direction of the aforesaid conveyor belt, for
feeding or gluing.
The expressions "low", "below", "lower" or "lower part", and
"high", "above", "upper" or "upper part" are used for indicating a
relative position with respect to the aforesaid conveyor belt, for
feeding or gluing.
The expressions "downstream" or "head", and "upstream" or "tail",
are used with reference to the aforesaid advancement direction.
Therefore, assuming for example an advancement direction from left
to right, a position "downstream" or "head" position with respect
to any one reference element indicates a position to the right of
said reference element and a position "upstream" or "tail" position
indicates a position to the left of said reference element.
By "image" or synonymously "digital image" a data set is generally
intended, typically contained in a computer file, in which each
coordinate (typically two-dimensional) of a finite set (typically
two-dimensional matrix, i.e. N lines.times.M columns) of spatial
coordinates (each typically corresponding to a pixel) is associated
with a corresponding set of numeric values (which can be
representative of magnitudes of different type). For example, in
monochromatic images (such as those with greyscale) such set of
values coincides with a single value in a finite scale (typically
with 256 levels or tones), such value being for example
representative of the brightness level (or intensity) of the
respective spatial coordinate when displayed, while in the colour
images the set of values represents the brightness level of a
multiplicity of colours, or channels, typically the primary colours
(e.g. red, green and blue in the RGB coding, while cyan, magenta,
yellow and black in the CMYK coding). The term `image` does not
necessarily involve the actual display of the same.
In the present description and claims, each reference to a specific
"digital image" (for example a two-dimensional digital image
initially acquired on a noise reducer element) more generally
comprises any one digital image obtainable through one or more
digital processing of said specific digital image (such as
filtering, equalisation, `thresholding`, morphological
transformations--`opening`, etc.,--gradient calculations,
`smoothing`, etc.).
In the present description and claims, each digital image is
considered to comprise a plurality of image units, i.e.
autonomously considerable image elements which constitute, overall,
the digital image; such image units can each be constituted by one
or more pixels. Each image unit corresponds with a respective
surface portion, the latter measured for example in mm.sup.2, of
the noise reducer element.
WO2016/067192 shows a process for applying a noise reducer element
to a tyre for vehicle wheels, comprising: a) arranging a noise
reducer element; b) arranging an adhesive material; c) guiding said
noise reducer element according to a predetermined direction; d)
during said guiding action, applying said adhesive material on a
first surface of said noise reducer element; e) manipulating said
noise reducer element by interacting with at least one second
surface of said noise reducer element different from said first
surface on which said adhesive material was applied; f) positioning
said noise reducer element in a predetermined position on a
radially inner surface of said tyre. EP2554617(A2) describes a
method for making a tyre comprising a noise reducer element. The
method comprises the steps of: applying an adhesive made of
silicone on the internal surface of the liner of the tyre in order
to form an adhesively-prepared surface, applying a solid foam noise
reducer element to the adhesively-prepared surface, and
cross-linking the adhesive.
WO2015/092659 describes a method and an apparatus for controlling
production and feeding of semi-finished products in a process for
building tyres, said method comprising: detecting at least one
first image representative of a semi-finished product wherein said
first image is composed of a plurality of first portions, each
associated with a respective brightness value; defining a first
threshold for said brightness values in a manner such that by
arranging a first linear scale of brightness values--defined
between a first value corresponding to a zero brightness value and
a second value corresponding to a maximum brightness value, in
which the absolute value of the difference between said first value
and said second value defines a range of said first scale--said
first threshold is such that the absolute value of the difference
between said first threshold and said first value is comprised
between about 5% and about 20% of the range of said first scale;
performing a first comparison between the brightness values of said
first portions and said first threshold; as a function of said
first comparison, determining a first operating parameter
representative of an overall area occupied in said first image by
the first portions associated with a brightness value smaller than
said first threshold; performing a second comparison between said
first operating parameter and a second threshold; if said first
operating parameter is less than or greater than said second
threshold, causing the generation of a first notification signal.
WO2015/092659 also describes an apparatus for controlling
production and feeding of semi-finished products in a process for
building tyres. In other words, WO2015/092659 proposes directing an
electromagnetic radiation on a semi-finished product with the shape
of a continuous elongated element with flattened cross section, and
detecting an image while the semi-finished product is unwound from
a reel and moved towards a station for building elementary
semi-finished products made by cutting the aforesaid semi-finished
product to size.
The Applicant has observed that the adhesive material applied on
the noise reducer elements is not always distributed in a uniform
manner and such non-uniformity of distribution can determine the
presence of areas of the noise reducer elements lacking adhesive or
in which there is insufficient adhesive or it is not optimally
coupled against the anchoring surface of the noise reducer
element.
The Applicant has observed that the lack or scarcity of adhesive in
some areas of the noise reducer elements or the imperfect adhesion
of the noise reducer elements to the tyre can determine a premature
partial or total detachment of such noise reducer elements from the
same.
The Applicant therefore perceived the importance of obtaining a
correct uniformity of the gluing of the noise reducer element to
the tyre.
The Applicant deems it opportune that in the production processes
for the tyres provided with noise reducer elements, suitable
examinations be performed in order to control the quality of the
gluing, ascertaining the correct application of the adhesive.
According to the Applicant, the identification of imperfections in
the application of the noise reducer elements already coupled to
the tyre is hard to perform, since the attachment interface between
the surfaces of each noise reducer element and of the tyre is
concealed therebetween.
The Applicant has observed that since it is thus necessary to
control each noise reducer element before its application on the
tyre, it is rather important to allow such control automatically
and reliably by means of a procedure that allows a perfect
repeatability of the control itself, without creating bottlenecks
within the entire tyre production process.
The Applicant has therefore perceived that the use of
electromagnetic radiations could be the optimal solution for
meeting the above-described needs.
The Applicant then in particular observed that the use of at least
one emission source of an electromagnetic radiation in the
direction of a surface of each noise reducer element provided with
adhesive (which will consists of the anchoring surface with the
tyre) and of at least one device adapted to receive such reflected
electromagnetic radiation, can allow an accurate, repeatable,
automatic and compatible control with the production cycle time
provided for the type of tyres comprising, on the radially inner
surface thereof, at least one of said noise reducer elements.
In particular, the Applicant has found that by means of arranging a
lighting system by means of electromagnetic radiations and
detection thereof on each noise reducer element provided with
adhesive it is possible to obtain an image that can be processed in
order to verify a suitable gluing. In such a manner, according to
the Applicant, it is possible to actuate a predictive control mode
suitable for preventing noise reducer elements in which the
adhesive is not correctly associated from being applied in the
tyre.
More particularly, according to a first aspect, the invention
relates to a process for applying noise reducer elements to tyres,
wherein each noise reducer element comprises an anchoring surface
coated with an adhesive layer.
Preferably, it is provided to illuminate said anchoring surface
coated with said adhesive layer with a reference radiation.
Preferably, it is provided to detect a radiation emitted by the
anchoring surface illuminated by the reference radiation.
Preferably, as a function of said emitted radiation it is provided
to determine a digital image representative of the anchoring
surface coated with said adhesive layer, each pixel of the digital
image being associated with a respective brightness value
representative of the quantity of adhesive present in an area of
said anchoring surface corresponding to said each pixel.
Preferably it is provided to calculate, as a function of the
brightness values, at least one first parameter representative of
the overall distribution of said adhesive layer on the anchoring
surface.
Preferably it is provided to perform a comparison between a value
of said at least one first parameter and at least one reference
value representative of a correct distribution of said adhesive
layer on the anchoring surface.
Preferably, based on said comparison it is provided to apply, on
the radially inner surface of a tyre, or direct along a discard
path, one or more noise reducer elements.
The Applicant deems that according to such solution, the production
discards can be limited to only the defective noise reducer
elements, avoiding the discard of the entire tyre.
The Applicant also deems that the gluing of the non-discarded
reducer elements of the tyre is thus always according to
specification, and therefore a separation from the tyre itself is
avoided notwithstanding the stresses imparted during operation,
even at high use speeds.
Typically, said radiation emitted by the anchoring surface
illuminated by the reference radiation is a reflected radiation,
though it may also be a diffused radiation and/or re-emitted
following at least partial absorption of the aforesaid reference
radiation.
In a second aspect, the invention relates to an apparatus for
applying noise reducer elements to tyres, wherein each noise
reducer element comprises an anchoring surface coated with an
adhesive layer.
Preferably, a lighting device is provided, configured for
illuminating said anchoring surface with a reference radiation.
Preferably a detection device is provided, configured for detecting
a radiation emitted by the anchoring surface illuminated by the
reference radiation.
Preferably, as a function of said emitted radiation, said detection
device is configured for determining a digital image,
representative of the anchoring surface coated with said adhesive
layer, each pixel of the digital image being associated with a
respective brightness value representative of the quantity of
adhesive present in an area of said anchoring surface corresponding
to said each pixel.
Preferably a processing unit is provided, configured for
calculating as a function of the brightness values at least one
first parameter representative of the overall distribution of said
adhesive layer on the anchoring surface.
Preferably a processing unit is provided, configured for performing
a comparison between a value of said at least one first parameter
and at least one reference value representative of a correct
distribution of said adhesive layer on the anchoring surface.
Preferably, based on said comparison, a processing unit is
provided, configured for controlling the activation of an
application device for applying, on the radially inner surface of a
tyre, one or more noise reducer elements or controlling a directing
along a discard path of one or more noise reducer elements.
In one or more of the aforesaid aspects, the invention can also
comprise one or more of the following preferred characteristics.
Preferably, it is provided that said illuminating action takes
place at a reading window.
Preferably, it is provided to position said noise reducer element
with its own anchoring surface resting against a first transport
surface movable according to a predetermined advancement
direction.
Preferably, it is provided to transfer the noise reducer element
from the first transport surface to a second transport surface
movable according to the advancement direction consecutively to the
first transport surface.
Preferably, it is provided that said illuminating action takes
place during said transferring action.
Preferably, it is provided that said reading window is defined
between the first transport surface and the second transport
surface.
Preferably, it is provided that said digital image comprises a
plurality of image units and the action of comparing the value of
said at least one first parameter with said at least one reference
value is performed for each image unit.
Preferably, it is provided that said digital image comprises a
plurality of image units and said comparison is performed as a
function of an acceptability threshold.
Preferably, said acceptability threshold comprises an absolute
acceptability parameter defined by a predetermined number of image
units for which the value of said at least one first parameter does
not conform to said at least one reference value.
Preferably, said acceptability threshold comprises a relative
acceptability parameter defined by a predetermined percentage of
image units for which the value of said at least one first
parameter does not conform to said at least one reference value,
with respect to the total number of image units of said digital
image.
Preferably, said acceptability threshold comprises an aggregative
acceptability parameter defined by a predetermined quantity of
image units that are respectively adjacent, for which the value of
said at least one first parameter does not conform to said at least
one reference value.
Preferably, the action of determining a digital image is carried
out by generating, during the transfer of each noise reducer
element, a plurality of frames each representative of a portion of
the anchoring surface.
Preferably, the action of determining a digital image is repeated
at a frequency defined as a function of the ratio of a transfer
speed of the noise reducer element along the advancement direction
to a longitudinal dimension of the reading window in the
advancement direction.
Preferably, a screen is provided, which is arranged adjacent to
said reading window, which when illuminated by the reference
radiation, emits a background radiation whose acquisition is
discriminable with respect to the radiation emitted by the
anchoring surface.
Preferably, it is provided to detect the background radiation
emitted by said screen, together with the radiation emitted by the
anchoring surface, discriminating in said digital image a first
portion representative of the anchoring surface and a second
portion representative of the screen.
Preferably, the action is provided, in detecting the amount of
image units for which the value of said at least one first
parameter does not conform to said at least one reference value,
for excluding the image units of the second portion representative
of the screen.
Preferably, it is provided to detect an alignment between a front
edge of the noise reducer element and a rear edge of the reading
window.
Preferably, it is provided to synchronise said action of
determining a digital image with the transferring of the noise
reducer element, as a function of the detected alignment.
Preferably, said lighting device works at a reading window.
Preferably, at least one first transport surface and one second
transport surface are provided, arranged consecutively.
Preferably, a positioning group is provided, configured for
positioning said noise reducer elements consecutively one after the
other each with its own anchoring surface resting against said
first transport surface.
Preferably, movement devices are provided, configured for
transferring each noise reducer element from the first transport
surface to the second transport surface according to an advancement
direction.
Preferably, said lighting device is configured for illuminating
said anchoring surface from an underlying position with respect to
said first transport surface and second transport surface at the
reading window.
Preferably, in the advancement direction, the reading window has a
longitudinal dimension smaller than a longitudinal dimension of
each noise reducer element.
Preferably, said detection device is configured for generating a
plurality of frames each representative of a portion of the
anchoring surface, determining said digital image during the
transfer of each noise reducer element by the movement devices.
Preferably, a screen is provided adjacent to the reading window,
such screen configured for emitting a background radiation
discriminable from the detection of the radiation emitted by the
anchoring surface, when reached by the reference radiation.
Preferably, the reading window is interposed between said screen
and said lighting device.
Preferably, said screen is configured for receiving the reference
radiation through the reading window.
Preferably, said screen is configured for emitting a background
radiation discriminable from the detection of the radiation emitted
by the anchoring surface when it is illuminated by the reference
radiation.
Preferably, said processing unit is configured for excluding image
units of the portion representative of the screen in detecting the
amount of image units for which the value of said at least one
first parameter does not conform to said at least one reference
value.
Preferably, the reference radiation is an infrared radiation having
wavelength comprised between about 850 nm and about 1050 nm.
Further characteristics and advantages will be clearer from the
detailed description of a preferred and non-exclusive embodiment of
the invention.
Such description is provided hereinbelow with reference to the
enclosed figures, also having merely exemplifying and hence
non-limiting purpose, in which:
FIG. 1 schematically shows a part of a plant for producing tyres in
which an apparatus is inserted in accordance with the present
invention;
FIG. 2 schematically shows, in side view, a detail of a part of the
apparatus of FIG. 1;
FIG. 3 schematically shows the detail of FIG. 2 seen from
above;
FIG. 4 schematically shows an exemplifying image used in the
apparatus and in the method according to the invention;
FIG. 5 shows, in an interrupted perspective view, a tyre provided
with noise reducer elements.
With reference to the enclosed figures, reference number 1 overall
indicates an apparatus for applying noise reducer elements to tyres
for vehicle wheels.
The apparatus is used for applying noise reducer elements 100.
As shown in particular in FIG. 1, a noise reducer element 100
comprises a block with parallelepiped form having an anchoring
surface 101 coated with an adhesive layer 50a.
The noise reducer element 100 is made of spongy material,
preferably made of polyurethane foam.
The presence of the adhesive layer 50a on the anchoring surface 101
confers to the latter different optical characteristics (e.g.
reflectivity and/or refractivity) with respect to the remaining
surfaces lacking adhesive layer 50a.
The apparatus 1 comprises a positioning group 2 through which the
noise reducer elements 100 are picked up by a suitable tank or by
another feeding unit, in order to receive, as better illustrated
hereinbelow, said adhesive layer 50a on the anchoring surface 101
and be transferred consecutively one after the other, each with its
own anchoring surface 101 resting against a first transport surface
10.
Preferably, the anchoring surface 101 and the first transport
surface 10 are respectively directed downward and upward.
In a preferred embodiment, the first transport surface 10 is
defined on an upper branch of a first conveyor belt 110.
The apparatus 1 also comprises at least one second transport
surface 20 consecutive to the first transport surface 10,
preferably aligned and coplanar with respect thereto.
The second transport surface 20 is preferably defined on an upper
branch of a second conveyor belt 120, consecutive and preferably
aligned with respect to the first conveyor belt 110.
The first transport surface 10 and the second transport surface 20
are movable according to a predetermined advancement direction A,
preferably at a same predetermined linear speed.
The assembly of the first conveyor belt 110 and second conveyor
belt 120 defines movement devices configured for transferring each
noise reducer element 100 from the first transport surface to the
second transport surface 20 according to the advancement direction
A.
In the illustrated example, the positioning group 2 comprises a
robotic arm 40 associated with a feeding belt 130 controlled by a
gluing belt 140, situated upstream of the first conveyor belt
110.
The robotic arm 40, e.g. of aerial type, bears a gripping member
suitable for sequentially picking up the noise reducer elements 100
in order to deposit them on the feeding belt 130. The feeding belt
130 transfers the noise reducer elements 100 to the gluing belt
140. A continuous strip-like support 50, on which an adhesive
coating 50a is arranged, is picked up by a feeding reel 51 and
wound on a collection reel 52, upon passage along an upper surface
of the gluing belt 140. Consequently, each of the noise reducer
elements 100 transferred on the gluing belt 140 receives the
respective adhesive layer 50a, picked up from the continuous
strip-like support 50 at the upper surface of the gluing belt
itself 140. A pressing element 60 can be used for facilitating the
transfer of the adhesive material 50a due to pressing action
exerted on the noise reducer elements 100 in the direction of the
gluing belt 140.
A cutting element 70 movable alternatively between the gluing belt
140 and the first conveyor belt 110 can be arranged for cutting the
adhesive material 50a and facilitating the mutual separation of the
noise reducer elements 100 which transit towards the first conveyor
belt 110.
With particular reference to FIGS. 1 to 3, the apparatus 1
comprises a reading window 30 preferably defined between the first
transport surface 10 and the second transport surface 20.
With reference to FIG. 3, in the advancement direction A, the
reading window 30 has a longitudinal dimension D1 delimited between
a front edge 30a and a rear edge 30b. The front edge 30a and the
rear edge 30b can be respectively defined by the mutually opposite
ends of the first conveyor belt 110 and of the second conveyor belt
120.
Preferably, the longitudinal dimension D1 is smaller than a
longitudinal dimension D2 of each noise reducer element 100. In one
embodiment of the invention, the reading window has longitudinal
dimension D1 comprised between about 30 mm and about 50 mm,
preferably of about 40 mm and the longitudinal dimension D2 of the
noise reducer element 100 is comprised between about 40 mm and
about 250 mm.
The size of the area to be controlled, delimited by the reading
window 30, varies as a function of the occupation of the window 30
by the noise reducer element 100.
More particularly, the area delimited reading window 30 varies as a
function of the fixed longitudinal dimension D1 and of a transverse
dimension D3 of the noise reducer element, variable in accordance
with the width presented by the noise reducer elements belonging to
a specific work batch.
The apparatus 1 comprises at least one lighting device 80,
operating through the reading window 30, and configured for
illuminating with a reference radiation R1 the anchoring surface
101 of each noise reducer element 100 which transits from the first
transport surface 10 to the second transport surface 20.
It is provided to illuminate the anchoring surface 101, coated with
the adhesive layer 50a, through the reading window 30, with the
reference radiation R1 and during the transfer from the first
transport surface 10 to the second transport surface 20.
In one embodiment, the lighting device 80 is configured for
illuminating the anchoring surface 101 from an underlying position
with respect to the first transport surface 10 and to the second
transport surface 20, through the reading window 30.
Preferably, the lighting device 80 comprises at least one lamp with
infrared emission.
Preferably, the reference radiation is infrared radiation having
wavelength comprised between about 850 nm and about 1050 nm.
Since the coating of the noise reducer element 100 with an adhesive
layer involves a variation of the optical characteristics of the
anchoring surface, it is possible to determine the correct
application of the adhesive layer by detecting a radiation emitted
by the noise reducer element 100 following the illuminating of the
anchoring surface 101.
With particular reference to FIG. 2, the apparatus 1 comprises a
detection device 90 configured for detecting the radiation R2
emitted by the anchoring surface 101 illuminated by the reference
radiation R1.
With particular reference to FIG. 4, the detection device 90 is
also configured for determining a digital image ImD as a function
of the emitted radiation R2; the digital image ImD is
representative of the anchoring surface 101 coated with the
adhesive layer 50a, each pixel of the digital image ImD being
associated with a respective brightness value representative of the
quantity of adhesive present in an area of said anchoring surface
corresponding to said each pixel.
Preferably, the digital image ImD comprises a plurality of image
units Ui, each representing one or more pixels corresponding to an
area of the anchoring surface 101 measured preferably in
mm.sup.2.
With particular reference to FIG. 3, the detection device 90 is
configured for detecting an alignment between a front edge 100a of
the noise reducer element 100 and a rear edge 30b of the reading
window 30.
The detection device 90 is also configured for synchronising the
determination of a digital image ImD with the transfer of the noise
reducer element 100, as a function of said alignment.
More in detail, with particular reference to FIG. 3, the detection
device 90 is configured for determining the digital image ImD
during the transfer of each noise reducer element 100 by the
movement devices and generating a plurality of frames Fi (F1, F2,
F3 and F4 in FIG. 4) each representative of a portion of the
anchoring surface 101.
Preferably, the total number N tot of the image units Ui of the
digital image ImD corresponds with the sum of the image units Ui
representative of the anchoring surface 101 in the single frames
Fi.
The detection device 90 is configured for predetermining the number
of frames Fi generated for each noise reducer element 100, as a
function of the longitudinal dimension D2 of the noise reducer
element 100.
In particular, the number of frames Fi generated for each noise
reducer element 100 corresponds with the ratio of the longitudinal
dimension D2 of the noise reducer element 100 to the longitudinal
dimension D1 of the reading window 30 in the advancement direction
A, rounded up to the next whole number. The detection device 90 is
also configured for determining the digital image ImD repeatedly,
at a frequency f defined as a function of the ratio of a transfer
speed V1 along the advancement direction A, imposed on the noise
reducer element 100 upon action of the movement devices, to a
longitudinal dimension D1 of the reading window 30 in the
advancement direction A.
The detection device 90, after having detected the radiation R2
emitted by the anchoring surface 101 illuminated by the reference
radiation R1, determines, as a function of said emitted radiation
R2, said digital image ImD representative of the anchoring surface
101 coated with said adhesive layer 50a. The emitted radiation R2
is variable as a function of the actual adhesion of the adhesive
layer 50a distributed on the anchoring surface 101.
The processing unit 200 (FIGS. 1 and 2) is configured for
calculating as a function of the brightness values at least one
first parameter P representative of the overall distribution of
said adhesive layer 50a on the anchoring surface 101. Subsequently,
the processing unit 200 performs a comparison between a value VP of
said at least one first parameter P and at least one reference
value Vrif representative of a correct distribution of said
adhesive layer 50a on the anchoring surface 101.
The value VP of said at least one first parameter P and its
comparison with at least one reference value Vrif, performed for
each pixel or image unit Ui, thus allows identifying the presence
of zones of the anchoring surface 101 in which there is no correct
adhesion of the adhesive layer 50a.
With particular reference to FIG. 1, the processing unit 200 is
also configured for controlling based on said comparison the
activation of an application device 180, operating downstream of
the reading window 30, in order to apply on the radially inner
surface of said tyre 500 one or more noise reducer elements
100.
The application device 180 can be structurally analogous to the
robotic arm 40, and selectively applies the noise reducer elements
100 in whose digital image ImD the comparison between the value VP
of said at least one first parameter P and at least one reference
value Vrif, as a function of an acceptability threshold Th, is
positive, i.e. when the adhesive layer 50a is correctly distributed
on the anchoring surface 101.
If the comparison between the value VP of said at least one first
parameter P and at least one reference value Vrif, as a function of
said acceptability threshold Th, is negative, i.e. when the
adhesive layer 50a is lacking or not correctly distributed on the
anchoring surface 101, the processing unit 200 is configured for
controlling, downstream of the reading window 30, the directing of
the noise reducer elements 100 along a discard path.
In the depicted example, the discard path leads to a collection
container 300, and in such case the noise reducer elements 100 pass
beyond a terminal end of the second conveyor belt 120 without being
picked up by the application device 180.
The comparison between the value VP of said at least one first
parameter P and at least one reference value Vrif is carried out
for each pixel or unit of image Ui.
In a first embodiment, the acceptability threshold Th comprises an
absolute acceptability parameter Th1 defined by a predetermined
number N1 of image units Ui for which the value VP of said at least
one first parameter P does not conform to said at least one
reference value Vrif.
It may be provided that the absolute acceptability parameter Th1
corresponds with the sum of the image units Ui for which the value
VP of said at least one first parameter P does not conform to said
at least one reference value Vrif in each single frame Fi or,
alternatively, in the sum of the frames which compose the digital
image ImD.
In a second embodiment, the acceptability threshold Th comprises a
relative acceptability parameter Th2 defined by a predetermined
percentage P1 of image units Ui for which the value VP of said at
least one first parameter P does not conform to said at least one
reference value Vrif, with respect to the total number N_tot of
image units Ui of said digital image ImD.
It may be provided that the relative acceptability parameter Th2
corresponds with the percentage of the sum of the image units
Ui for which the value VP of said at least one first parameter P
does not conform to said at least one reference value Vrif in each
single frame Fi, with respect to the total number N_tot of image
units Ui of the digital image ImD.
In a third embodiment, the acceptability threshold Th comprises an
aggregative acceptability parameter Th3 defined by a predetermined
quantity Q1 of image units Ui that are respectively adjacent, for
which the value VP of said at least one first parameter P does not
conform to said at least one reference value Vrif.
Preferably, the predetermined quantity Q1 of image units Ui, which
are respectively adjacent defining the third acceptability
threshold Th3, is lower than the predetermined number N1 of image
units Ui defining the first acceptability threshold Th1.
In other words, it can be provided that a lower but concentrated
number of detected defects can refer to a more stringent
acceptability threshold.
It can be provided that the aggregative acceptability parameter Th3
corresponds with the sum of the image units Ui that are
respectively adjacent, for which the value VP of said at least one
first parameter P does not conform to said at least one reference
value Vrif in two or more respectively consecutive frames.
With particular reference to FIGS. 1 and 2, the apparatus comprises
a screen 111, adjacent to the reading window 30.
In particular, the reading window 30 is preferably interposed
between the screen 111 and the lighting device 80.
The screen 111 is configured for receiving the reference radiation
R1 through the reading window 30.
When it is reached by the reference radiation R1, it is provided
that the screen 111 emits a background radiation R3 whose
acquisition is discriminable with respect to the radiation R2
emitted by the anchoring surface 101.
With particular reference to FIG. 4, the detection device 90 is
configured for detecting the background radiation R3, emitted by
the screen 111, together with the radiation R2 emitted by the
anchoring surface 101, and for discriminating in the digital image
ImD a first portion A1 representative of the anchoring surface 101
and a second portion A2 representative of the screen 111.
With particular reference to FIG. 4, the processing unit 200 is
configured for excluding the image units Ui of the second portion
A2 representative of the screen 111, for the purpose of the
detection of the amount of image units Ui for which the value VP of
said at least one first parameter P does not conform to said at
least one reference value Vrif.
In one embodiment of the process according to the invention, the
following were considered: the pixel brightness value equal to 0 in
case of total absence of adhesive on the noise reducer element and
comprised between 50 and 255 for a sufficient presence thereof
(i.e. Vrif.gtoreq.50); an area smaller than 100 mm.sup.2 relative
to those portions of the anchoring surface of the noise reducer
element on which the adhesive is not correctly distributed, i.e.
such that the corresponding pixels thereof have brightness value
lower than 50, the threshold for the acceptability of the noise
reducer element itself (threshold Th).
According to the aforesaid embodiment, a noise reducer element 100
with 120 mm.times.220 mm size having its own anchoring surface 101,
on which the adhesive layer 50a has been applied, was transferred
according to the advancement direction A from the first transport
surface 10 to the second transport surface 20. Illuminated by the
radiation R1, having wavelength equal to about 900 nm, the digital
image ImD obtained according to the illustrated process showed two
surface portions, respectively of about 49.7 mm.sup.2 and 29.7
mm.sup.2, in which the distribution of the adhesive was scarce or
absent, i.e. brightness values lower than 50 of the corresponding
pixels (generating the first parameter P each time compared with
Vrif), identified, on the anchoring surface, a corresponding
overall surface portion of 79.4 mm.sup.2. The noise reducer element
was thus deemed acceptable and was applied inside a tyre.
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